1. Homework: pg. 119 #3,4; pg. 122 #6-8
3.) A. Judy’s bone density score is about one and a half standard deviations below the average score for all women her age. B ) A. Mary’s z-score indicates that her bone density score is about a half standard deviation above average for all women her age. Mary’s bones are healthier when comparisons are made to other women’s in their age groups. B. 8; there is more variability in the bone densities for older women, which is not surprising.

2. 6. ) A. The rate of unemployment in IL increased from 28. 89% from Dec
6.) A. The rate of unemployment in IL increased from 28.89% from Dec (4.5%) to May 2005 (5.8%). B. The z-score in Dec (1.03) is higher than the z- score in May 2005 (0.9262) C. 86th in Dec. 2000; 84th in May 2005; dropped one spot on the list. 7.) A. Scott’s percentiles: 94.8th national, 68th local B. National: 1.57; local: 0.62 C. Well; Scott’s score was relatively better when compared to the national group than to his peers in his school. D. SKIP 8.) being in the 90th percentile is not good news in this situation. About 90% of men similar to Larry have identical or lower blood pressure.

3. 2.1 Density Curves

4. Density curve density curve— describes the overall
pattern of distribution
always on or above horizontal axis
Total AREA under the curve is 1

5. Density Curve pg 125—Figure 2.5
Means 12% of the observations have values between 7 and 8

6. Median and Mean
Median of Density Curve—it is the “equal area point,” divides the area under the curve in half
Mean of Density Curve— it is the “balance point,” curve would balance if solid

7. Notation English letters are used for samples (called Statistics):
Greek letters are used for the population (called Parameters):

8. Example: Use graph to answer the questions
1. Verify that this is a density curve 2. What is the proportion of observations within each interval? 2 4 .2 .4

9. Against All Odds
An Introduction to the Normal Distribution

10. HW: pg 128 #10,13 pg. 132 #19,20